The present disclosure generally relates to depth sensing, and specifically relates to circularly polarized illumination and detection for depth sensing.
To achieve compelling augmented reality (AR) and virtual reality (VR) user experiences, it is desired to create a depth sensing device that can determine a dense three-dimensional mapping in both indoor and outdoor surroundings. A depth camera usually involves structured light illumination, which is a triangulation technique that makes use of an active illumination source to project known patterns into a scene. The depth camera typically utilizes a two-dimensional pixel array detector to measure and record light back-scattered from one or more objects in the scene. Other methods for depth sensing are based on a time-of-flight technique, which measures a round trip travel time-of-light projected into the scene and returning to pixels on a sensor array. The problem related to the depth sensing methods based on structured light illumination and time-of-flight is related to designing a compact and efficient depth camera that can produce quality depth maps in both indoor and outdoor environments where background ambient light can strongly interfere depth measurements. The depth map obtained in these environments typically have large depth errors and a low level of signal-to-noise ratio (SNR) due to the strong background ambient light.